IE922231A1 - Device for supplying electricity by contact with a wiper and¹method for manufacturing such a device - Google Patents

Abstract

The present invention relates to a device for supplying electric power by contact with a contact brush (slide) as well as a process for manufacturing such a device. The device (1) comprises an electrically-conducting mounting body (2) coated, with a view to contacting the contact brush (slide) (6), an electrically-conducting wear film (3) comprising an electrically-conducting material having a Vickers hardness value at least equal to 1000 and a melting point at least equal to 2000 DEG C. Such a device can form a rail or a wire for supplying a vehicle with electric power, or even a slip (collector) ring.

Description

The present invention relates to a device for supplying electricity by contact with a wiper, the device and the wiper being given a relative mutual sliding motion during which the wiper executes a specified trajectory on the device, the device comprising a fixture body which is electrically conductive and a wear strip which is electrically conductive covering the body along said trajectory, in a manner which is uniformly integral, and having greater abrasion resistance than that of the body.

By way of non-limiting examples of such devices, can be cited rails intended for the electrical supply of certain railroad vehicles, certain funiculars, certain merry-go-rounds, certain machines comprising equipment which is moveable in translation or in rotation, or even catenaries used for supplying certain railroad vehicles in which a homed slipper of a pantograph usually fulfills the role of wiper, namely both the flexible catenary wires and the rigid catenaries used especially in tunnels, or even the collector rings used in order to ensure electricity transfer between a fixed portion of a machine such as a merry-go-round or a carousel and a portion of this machine which is mounted rotatably about an axis determined with respect to the fixed portion.

In that which concerns electric supply rails, US-A-3 836 394 proposes that a strip of stainless steel be manufactured by electric arc metallization or plasma spraying, which strip is intended to serve as contact with the wipers on a body which is itself manufactured in the form - of an extruded aluminum profiled part. This body, intended for the fixture of the supply rail on supports such as isolators, has, in a direction which is transverse to a longitudinal direction and is common with the strip, a cross section which is determined, on the one hand, as a function of the rigidity which it is desired to give to the supply rail, and on the other hand, as a function of the current which it is desired to make the latter carry; in this respect, aluminum and its alloys have the advantage of good electrical conductivity along with good thermal conductivity, making it possible to rapidly dissipate the local excess heat due to inevitable electric arcs which arise by accident between the wiper and the stainless steel strip, given that they can be replaced in this respect by other materials such as copper and its alloys which, however, have the drawback of a greater density, leading to an increase in weight for a specified transverse section.

The stainless steel strip, which is more resistant to abrasion than aluminum and its alloys or copper and its alloys, makes it possible to extend the lifespan of the supply rail by limiting its wear due to the friction of the wiper, but stainless steel has the drawback of not being such a good conductor of electricity and of heat as aluminum and its alloys or copper and its alloys and of being more dense than them; because of this, the thickness of this strip is limited to the value necessary to ensure a minimum specified operational time before complete wear and, in this respect, US-A-3 836 394 recommends a thickness of between 0.3 and 2 mm.

This thickness, dictated by the desire to give the electrical supply rail a suitable lifespan, has the drawback of being too great in two respects, namely with regard to the method for electric arc metallization or plasma spraying which becomes particularly costly to implement for such thicknesses, even if the choice of such a method is justified in itself by the effectiveness of the anchoring of the strip on the body which it makes it possible to obtain, and with regard to the high electrical resistance and the mediocre thermal conductivity which results therefrom taking into account the physical characteristics of stainless steel, which leads, on the one hand, to energy losses, and on the other hand, to local heating, which gives rise to erosion, under the effect of electric arcs appearing between the wiper and the strip.

The object of the present invention is to over20 come these drawbacks and, to this effect, it proposes a device of the type indicated in the preamble, wherein moreover the wear strip comprises an electrically conductive material having a hardness at least equal to 1000 Vickers and a melting temperature at least equal to 2000eC.

This substantially increased hardness, in comparison with that of stainless steel, rendering the strip more resistant to wear, and this melting temperature which is substantially higher than that of stainless.steel, rendering the strip much less vulnerable to electric arcs than the latter and especially avoiding the effects of electro-erosion, make it possible to considerably extend the longevity of the strip and of the electrical supply device as a whole and, because of this, to substantially reduce the thickness of the strip for even more increased longevity, in comparison with an electrical supply rail manufactured in accordance with the teachings of US-A-3 836 394.

In fact, under these conditions it can be permissible for the strip to have a thickness between about 50 and 300 μτα, preferably between about 100 and 150 pm, the choice of the minimum value being essentially dictated by the desire to avoid porosity which would allow the passage of external agents, which give rise to corrosion especially by electrolysis, between the strip and the body, and the choice of the upper value being essentially dictated by consideration of economics, given that the hardness and the melting temperature recommended according to the present invention for the wear strip make it possible to give the electrical supply device a suitable longevity even for the smallest values of the thickness of this wear strip.

The reduction which is thus possible in the thickness of the wear strip, in comparison with the stainless steel strip described in US-A-3 836 394, makes it possible on the one hand, to apply methods for molten state spraying of the electric arc metallization type or of the plasma spraying type, or similar methods, under good conditions with a view to manufacturing this strip, and on the other hand, for given electrical resistivity and thermal conductivity of the material constituting the wear strip, to benefit both from the electrical resistance of the latter, which is as low as possible, reducing energy losses as well as the heating which results therefrom, and from thermal conduction which is as good as possible across the wear strip, between the wiper and the fixture body of the supply device, in order to permit the rapid dissipation of local heating resulting from electric arcs which can arise between the wiper and the wear strip, which avoids the electroerosion phenomena and consequently increases the longevity of this strip even more.

The nature of the wear strip, in the limits especially of hardness and of melting temperature which are characteristic of the present invention, can vary over a wide range, given that in each case for the manufacture of this wear strip a material will be chosen having, on the one hand, as low a resistivity as possible and as high a thermal conductivity as possible, and on the other hand, good resistance to oxidation in the normal environment of using the electrical supply device.

Thus, it is possible to manufacture the strip in homogenous form, from a homogeneous metal alloy or metal and for example from molybdenum or tungsten.

It can also be manufactured in a form comprising grains of a material having said hardness and said melting temperature, which are characteristic of the invention., embedded in an electrically conductive binding matrix, having a hardness and melting temperature less than those of said material; for example, the material constituting the grains can be chosen within a group comprising the carbides of tungsten, of titanium, of chromium, of molybdenum and the matrix can be manufactured in a material chosen within a group comprising cobalt, nickel, chromium, copper, aluminum and their alloys, these examples being in no way limiting.

In such a case, the electrical supply device according to the invention can advantageously be manufactured by a method wherein the wear strip is applied onto the fixture body by spraying at a temperature intermediate between the respective melting temperatures of the material of the grains and of the matrix, given that with a view to the spraying and the getting to a suitable temperature, a method suitably chosen within the known methods of molten state spraying, such as electric arc metallization, plasma spraying or other similar methods could be used; such a spraying at a temperature intermediate between the respective melting temperatures of the material of the grains and of the matrix makes it possible to conserve the characteristics of the grains by avoiding their heating, whilst at the same time causing the matrix to melt, in order to then ensure its effective binding with the fixture body, as well as with the grains in order to firmly bind the latter to the fixture body.

The latter can itself be constituted, in a traditional fashion, from a material chosen within a group comprising aluminum and its alloys as well as copper and its alloys.

Preferably, the integralization of the wear strip 5 with the fixture body is direct, and for example obtained by spraying the wear strip, in the totally or partially molten state, directly onto the fixture body; however, an indirect integralization, that is to say by the intermediary of an anchoring strip chosen and applied in a manner so as to uniformly anchor onto the fixture body and to lend itself to a uniform anchoring of the wear strip, and then to resist the, especially thermal, conditions of use and to have electrical resistance which is as low as possible and a thermal conductivity which is as high as possible may also be permitted. This anchoring strip can advantageously be applied, like the wear strip, by a method of spraying in the molten state.

It will be noted that a device according to the invention can have various shapes, corresponding to various modes of electrical supply by contact with a wiper, conferring the same advantages.

Thus, a device according to the invention can constitute a rail or a wire for the electrical supply to a locomotive, in which case the body and the strip have shapes which are respectively elongated along a same longitudinal direction and have substantially constant transverse cross sections, respectively relatively large and small, the cross section of the fixture body being dictated by the rigidity which it is desired to give to it, on the one hand, and by the role which it is desired that it should fulfill in the dissipation of local heat which could appear due to electric arcs between the wiper and the wear strip.

The device according to the invention can also constitute a collector ring, in which case the fixture body has an axis and the strip has a shape of revolution about this axis.

Other characteristics and advantages of the 10 electrical supply device according to the invention as well as of the method recommended in accordance with the present invention for the manufacture of such a device will emerge from the description below, relating to three non-limiting examples of implementation, as well as from the appended drawings which form an integral part of this description.

- Figure 1 shows a view in perspective of an electrical supply rail in accordance with the present invention.

- Figure 2 shows a view in perspective of a catenary wire in accordance with the present invention.

- Figure 3 shows a view in perspective of a collector ring in accordance with the present invention.

- Figure 4 shows a view in transverse cross 25 section of another electrical supply rail in accordance with the present invention.

In the first instance, reference will be made to Figure 1, where there has been illustrated the manufacture of a longitudinal electrical supply rail 1, comprising two longitudinal components, mutually set next to each other transversely and mutually integralized in a direct and uniform fashion, that to say without intermediate material and without discontinuity between them, namely a fixture body 2 manufactured for example in the form of a longitudinal profiled part made of aluminum or aluminum alloy, or even of copper or of copper alloy, and a continuous wear strip or film 3, advantageously manufactured by molten state spraying onto a longitudinal face 4 of the fixture body 2, which face 4 has in the example illustrated a flat shape but could have different shapes, convex or concave, in other embodiments of the invention; the fixture body 2 and the wear strip 3 have respective constant transverse cross sections, respectively I-shaped and rectangular in this non-limiting example, the strip 3 having perpendicularly to the face 4 a uniform thickness e between about 50 and 300 μτα, and preferably between about 100 and 150 μτα, these numbers still being indicated by way of a non20 limiting example.

In accordance with the present invention, the strip 3 comprises an electrically conductive material having a hardness at least equal to 1000 Vickers and a melting temperature at least equal to 2000°C, either because it is integrally manufactured in such a material, which can be a metal such as molybdenum or tungsten or an alloy, or because it comprises grains of such a material, such as a carbide of tungsten, of titanium, of chromium, of molybdenum embedded in an electrically conductive - 10 binding matrix ensuring the binding of the grains between themselves and with the face 4 of the body 2, and having a hardness and a melting temperature less than those of the grains, which makes it possible to manufacture the wear strip 3 on the face 4 of the fixture body 2 by spraying at a temperature intermediate between the respective melting temperatures of the material of the grains and of the matrix; to this end, for example, it can be chosen to manufacture the matrix from cobalt, nickel, chromium, copper, aluminum or from alloys of these metals, given that other choices would not depart from the scope of the present invention, just as the scope of the present invention would not be departed from by choosing for the grains materials other than carbides of tungsten, of titanium, or of chromium.

The strip 3 thus constituted has, parallel to the face 4 of the fixture body 2, a free face 5 which has the same orientation as the face 4 from which is spaced by the thickness e of the strip 3 and which is intended for the longitudinal sliding of a wiper 6; by way of a nonlimiting example, when the rail according to the invention 1 is intended to supply electricity to a railroad vehicle, the wiper 6 is mounted laterally on this railroad vehicle, not shown, and the rail according to the invention 1 is mounted on the ground, along the railroad track, by the intermediary of electrically isolating supports; naturally, this example of the application of a rail according to the invention 1 is in no way limiting.

A. person skilled in the art will easily understand that in a similar fashion a rigid catenary could be manufactured.

Reference will now be made to Figure 2, where 5 there has been illustrated a longitudinal catenary wire 7 according to the invention comprising especially a longitudinal fixture body 8 which can be of the same nature as the fixture body 2 of the electrical supply rail 1. This fixture body 8 has a constant transverse cross section suitable for allowing it to be mounted, for example by pinching, on supports which are not shown, namely in the example illustrated a transverse cross section comprising an upper zone 9 and a lower zone 10, if reference is made to a normal orientation for using the wire 7, the upper zone 9 having a dovetail contour and the lower zone 10 having an approximately rectangular contour such as to define at their junction, respectively on either side of the wire 7, two longitudinal grooves 11 for receiving a support ensuring the retention of the wire 7 by pinching, in a manner which is not shown but which is easily envisaged by a person skilled in the art.

The lower zone 10 of the transverse cross section of the fixture body 8 is thus defined by a lower longitudinal convex face 12 and by two lateral longitudinal flat faces 13, which are mutually parallel and opposite in such a fashion as to define with the lower longitudinal face 12, in the transverse cross section of the fixture body 8, a U-shape.

In accordance with the present invention, the lower longitudinal face 12 of the fixture body 8 and its two lateral longitudinal faces 13 are covered, in a directly and uniformly integral fashion, with a continuous wear strip or film 14, in every way comparable with the wear strip 3 of the rail 1 and especially having like the latter strip a constant thickness e advantageously between about 50 and 300 pm, preferably between about 100 and 150 pm, with a hardness at least equal to 1000 Vickers and a melting temperature at least equal to 2000°C.

The wear strip 14 thus has, respectively towards the bottom and laterally, a convex lower face 15 intended for contact with the homed slipper 16 of a pantograph, not shown, of a locomotive moving longitudinally in contact with this face 15, and two flat lateral faces 17, mutually parallel and opposite, to which the face 15 is laterally connected, towards the top.

Naturally, this shape of a catenary wire 7 only constitutes a non-limiting example and the scope of the present invention would not be departed from by choosing other shapes.

Reference will now be made to Figure 3, where there has been illustrated a collector ring 18 comprising a fixture body 19 having at least locally, and for example wholly, a symmetry of revolution about an axis 20 about which, for example, it is mounted in rotation about a fixed part not shown, together with a movable part also not shown, in order to permit a transfer of electricity between the two parts.

To this end, the body 19, which can be manufactured in any of the materials indicated in regard to the fixture body 2 of the rail 1, has, on a face 21 having a shape of revolution about the axis 20 and for example cylindrical of revolution about this axis, a continuous wear strip or film 22, of uniform thickness e advantageously between about 50 and 300 μία, and preferably between about 100 and 150 pm, integralized directly and uniformly with the face 21 of the body 19 and having the characteristics described in regard to the wear strip 3 of the rail 1? thus, the wear strip 22 has parallel to the face 21 and according to an orientation identical to that of the latter a free face 23, also of revolution about the axis 20 and for example cylindrical of revolution about this axis 20, with a view to contact with a wiper 24 borne, in this example, by the fixed part not shown.

Like the wear strip 3, the wear strips 14 and 23 are advantageously manufactured by spraying, in the molten state, respectively on the faces 12 and 13 of the fixture body 8 and on the face 21 of the fixture body 19, in such a fashion as to ensure direct and uniform integralization of these wear strips 14 and 22 with the respectively corresponding fixture body 8, 19.

Finally reference will be made to Figure 4, where there has been illustrated a variant of an electrical supply rail according to the invention, namely a longitudinal electrical supply rail 25 suitable for guiding the wiper 26 with which it interacts, which is for example borne by a moving body, not shown, such as a railroad vehicle, moving longitudinally alongside the rail 25 which is itself fixed with respect to the ground.

To this end, the rail 25 comprises a fixture body 5 27 manufactured in the shape of a longitudinal profiled part made of any one of the materials indicated in regard to the fixture body 2 of the rail 1; this fixture body 27 has a constant transverse section for example in the shape of an H, defined by two mutually parallel flanges 31 joined mutually by a web 32, in such a fashion as to be incorporated in an electrically insulating envelope 28 leaving a longitudinal slot 29 for access, by the wiper 26, to a longitudinal face 30 of the web 32 and this longitudinal face 30 has a concave, V-shape in the transverse cross section of the fixture body 27.

In accordance with the present invention, the face 30 is covered, in a directly and uniformly integral fashion, with a continuous wear strip or film 33 of uniform thickness e advantageously between about 50 and 300 μία, and preferably between about 100 and 150 μΐη, having the characteristics described in regard to the wear strip 3 of the rail 1; thus, the wear strip 33 has, in contact with the wiper 26, two flat longitudinal faces 34 defining a concave transverse section, in the shape of a V, in which the wiper 26 is wedged against transverse displacements and which thus ensures the longitudinality of the trajectory followed by the wiper 26 with respect to the rail 25.

The wear strip 33 is advantageously manufactured by spraying, in the molten state.

A person skilled in the art will easily understand that the embodiments of a device according to the invention which have just been described only constitute non-limiting examples, with respect to which numerous variants can be envisaged, especially in shape, without in any way departing from the scope of the present invention; moreover, a person skilled in the art will easily understand that, although it is preferred to render the wear strips or films directly integral with the fixture body as has been described with reference to Figures 1 to 4, an indirect mutual integralization could also be envisaged, that is to say by the intermediary of an electrically and thermally conductive anchoring strip or film, naturally chosen and applied, like the wear strip, such as to guarantee uniformity of the anchoring of the wear strip on the fixture body and to resist the, especially thermal, conditions of use; in particular, this anchoring strip will preferably be applied like the wear strip by a method of spraying in the molten state, over a thickness which is as small as possible.

Claims (14)

1· A device for supplying electricity by contact with a wiper (6, 16, 24, 26), the device (1, 7, 18, 25) and the wiper (6, 16, 24, 26) being given a relative 5 mutual sliding motion during which the wiper (6, 16, 24, 26) executes a specified trajectory on the device (1, 7, 18, 25), the device (1, 7, 18, 25) comprising a fixture body (2, 8, 19, 27) which is electrically conductive and a wear strip (3, 14, 22, 33) which is electrically 10 conductive covering the body (2, 8, 19, 27) along said trajectory, in a manner which is uniformly integral, and having greater abrasion resistance than that of the body (2, 8, 19, 27), wherein the strip (3, 14, 22, 33) comprises an 15 electrically conductive material having a hardness at least equal to 1000 Vickers and a melting temperature at least equal to 2000®C.

2. The device as claimed in claim 1, wherein the strip (3, 14, 22, 33) has a thickness between about 50 20 and 300 μία, preferably between about 100 and 150 pm.

3. The device as claimed in either of claims 1 and 2, wherein the strip (3, 14, 22, 33) is directly integral with the body (2, 8, 19, 27).

4. The device as claimed in any one of claims 1 to 25 3, wherein the strip (3, 14, 22, 33) is a homogenous strip made of a material having said hardness and said melting temperature.

5. The device as claimed in claim 4, wherein said material is chosen within a group comprising molybdenum IE 92223 1 - 17 and tungsten.

6. The device as claimed in any one of claims 1 to 3, wherein the strip (3, 14, 22, 33) comprises grains of a material having said hardness and said melting 5 temperature, embedded in an electrically conductive binding matrix, having a hardness and a melting temperature less than those of said material.

7. The device as claimed in claim 6, wherein said material is chosen within a group comprising the carbides 10 of tungsten, of titanium, of chromium, of molybdenum.

8. The device as claimed in either of claims 6 and 7, wherein the matrix is chosen within a group comprising cobalt, nickel, copper, aluminum and their alloys.

9. The device as claimed in any one of claims 1 to 15 8, wherein the body (2, 8, 19, 27) is made of a material chosen within a group comprising aluminum and its alloys, copper and its alloys.

10. The device according to any one of claims 1 to 9, wherein it constitutes a rail (1, 25) or a wire (7) for 20 the electrical supply to a moving body, and wherein the body (2, 8, 27) and the strip (3, 14, 33) have shapes which are respectively elongated along a same longitudinal direction and have substantially constant transverse cross sections, respectively relatively large 25 and small.

11. The device as claimed in any one of claims 1 to 9, wherein it constitutes a collector ring (18), wherein the body (19) has an axis (20) and wherein the strip (22) has a shape of revolution about this axis (20). •Ε 922231

12. A-method for manufacturing a device as claimed in any one of claims 6 to 8, wherein the wear strip (3, 14, 22, 33) is applied onto the fixture body (2, 8, 19, 27) by spraying at a temperature intermediate between the 5 respective melting temperatures of the material of the grains and of the matrix.

13. A device for supplying electricity by contact with a wiper substantially as herein described with reference to the accompanying drawings .

14. A method of manufacturing a device as claimed in any one of claims 6 to 8 substantially as herein described.